You previously said:
"In order to test, one must DESIGN the system to be easy to test."
I took that to mean that elements were being added into the system in order to assist the user in testing. However, after reading your last post, I get the impression that the added elements are to assist the programmer in debugging.
Am I right? If the elements are added for debugging, then we have a whole different ballgame than elements added for user testing. For debugging purposes, I think that these elements are a lot easier to develop because the audience is the programmer himself who has a thorough understanding of the system. And, yes, I agree that the system should be designed that way, otherwise, debugging will not be complete.
To add elements to assist user testing, although this sounds like a good idea, I think would be far more difficult.
So, which testing are you addressing, debugging, user testing, or both?